I think sallabanas has got this situation analysed correctly.
He may have realised that he is getting into a serious relationship with you, which will involve commitment, and he may just be scared, and have run off, which is neither adult, or expecially kind.
He may come back, burt if not, mark it down to his feelings, and not to anything you did or did not do.
Sadly, in order to find any kind of meaningful relationship, you need to put yourself out there, with the risk of being hurt in the process.
Put anohter way - you will find a prince, but you do have to kiss a lot of frogs first!